This invention relates to the removal and recovery of carbon monoxide from feedstreams. More particularly, carbon monoxide is removed from feedstreams by formation of a complex with Cu(I)-fluorinated acetylacetonate in the presence of a stabilizing agent which prevents disproportionation of the complex to copper metal during recovery of carbon monoxide.
It is well-known that cuprous salt solutions will absorb carbon monoxide (CO). A review of the early literature relating to this topic may be found in J. Appl. Chem. (London), 15, 17-28(1965). It is also known that certain silver(I) and copper(I) salts form complexes with olefins and acetylenes. For example, cuprous chloride is known to form complexes with both ethylene and acetylene. U.S. Pat. No. 3,401,112 teaches a method of separating a mixture of hydrocarbons having differing degrees of unsaturation using a copper(I) salt of the formula CuXA where XA is an anion, X is oxygen or fluorine and A is the remainder of the anion. Examples of fluorinated anions include fluoro substituted carboxylates, fluorosulphonate, perfluoroborate, hexafluorophosphate and hexafluoroantiomonate. CuXA forms a cuprous complex with said unsaturated hydrocarbon. Similarly, U.S. Pat. No. 3,517,079 describes a process for separating vinyl aromatic hydrocarbons from alkyl aromatic hydrocarbons using a cuprous fluoroborate or cuprous fluorophosphate salt wherein a complex is formed. U.S. Pat. Nos. 3,754,047 and 3,755,487 relate to a process for separating complexible ligands such as olefins, acetylenes, aromatics and CO from a feedstream using cuprous salts such as CuAlCl.sub.4, CuBF.sub.4, CuOOCCF.sub.3, CuPF.sub.6 and the like. A process for separating CO from gas mixtures using copper(I) salts of sulfonic acids or dialkyl phosphates is disclosed in U.S. Pat. No. 4,042,669. U.S. Pat. No. 4,048,292 teaches a method for preparing high purity CO from CO.sub.2 -free gas streams using a copper ammonium C.sub.1 -C.sub.2 acetate as the absorbent medium. Finally, U.S. Pat. No. 4,279,874 describes a process for removing CO from a gas stream wherein the gas stream is contacted with an absorbent solution containing a Cu(I) complex with halogenated beta-diketonate as ligand thereby removing CO as a carbonyl-Cu(I)-halogenated beta-diketonate complex.
The known processes for removing CO by Cu(I) complex formation suffer from one or more disadvantages such as high corrosivity, low reactivity to CO, high energy cost to regenerate CO, low selectivity to CO, instability of the absorbent system and formation of Cu metal during regeneration of absorbent solution. It would be highly desirable to have a method for selectively and efficiently removing CO and unsaturated hydrocarbon from a feedstream while at the same time being able to regenerate the absorbent system under mild conditions without formation of copper metal.